GROUP BY and ORDER BY

[Experienced but Undocumented]

Here's another one; thanks so much to everyone who helped with my last
problem. I can't upgrade mySQL but I figured out a way around it from your
examples.

SELECT `subject` , max( `datetime` )
FROM `table`
WHERE 1
GROUP BY `subject`
ORDER BY `datetime` DESC LIMIT 0 , 30

The thing is...it doesn't order by `datetime`...it seems to be in a random
order. I've tried ORDER BY max(`datetime`) but that gives me an error that
says "#1111 - Invalid use of group function"

I could just sort it in PHP, but is there a better way?

Thanks

[Siemel Naran]

"Experienced but Undocumented" <e0*@removethis.toao.net> wrote in message

Here's another one; thanks so much to everyone who helped with my last
problem. I can't upgrade mySQL but I figured out a way around it from your examples.

SELECT `subject` , max( `datetime` )
FROM `table`
WHERE 1
GROUP BY `subject`
ORDER BY `datetime` DESC LIMIT 0 , 30

The thing is...it doesn't order by `datetime`...it seems to be in a random
order. I've tried ORDER BY max(`datetime`) but that gives me an error that says "#1111 - Invalid use of group function"

I could just sort it in PHP, but is there a better way?

Use column aliases.

SELECT `subject` , max( `datetime` ) as mdi
FROM `table`
WHERE 1
GROUP BY `subject`
ORDER BY mdi DESC LIMIT 0 , 30

Incidentally, what is meaning of the apostrophe `

[Experienced but Undocumented]

"Siemel Naran" <Si*********@REMOVE.att.net> wrote

Use column aliases.

SELECT `subject` , max( `datetime` ) as mdi

Perfect! Thanks so much for your help!